The Evolved Packet Core (EPC) is the core network of advanced mobile communication systems. The EPC allows different radio access technologies (RATs) to operate in an integrated manner. These radio access technologies include first generation wireless Local Area Networks (LANs), second generation (2G) systems, such as Global System for Mobile communication, or GSM, third generation (3G) systems, such as the Universal Mobile Telecommunication System (UMTS), and fourth generation (4G) systems, such as Long Term Evolution (LTE).
FIG. 1 is a basic architecture of an Evolved Packet System (EPS) 80. An User Equipment (UE) 50 connects to the EPC 70 over the LTE access network known as E-UTRAN (short for Evolved UMTS Terrestrial Radio Access Network) 44 and communicates with a base station known as the Evolved Node B (eNB) 40. EPS generally refers to a complete system consisting of the UE, the EUTRAN, and the core network (EPC).
The EPC is a packet-switched network in which the Internet Protocol (IP) is used for all transport services. The EPC is part of the 3rd Generation Partnership Project (3GPP) specification.
The EPC 70 consists of a Serving Gateway (S-GW) 30, a Packet Data Network Gateway (P-GW) 32, a Mobility Management Entity (MME) 34, and a Home Subscriber Server (HSS) 36. The EPC 70 connects to external networks 38, in this case, including an Internet Protocol Multimedia Subsystem (IMS) 42. User data and signaling are independent, with user data occupying a user plane (solid lines) and signaling occupying a control plane (dashed lines).
LTE in unlicensed spectrum (LTE-U) is a proposal for the use of unlicensed spectrum by LTE devices. The unlicensed spectrum consists of the 5 GHz band used by WiFi devices. Cellular devices are usually limited to the part of the radio spectrum in which they are licensed. LTE-U allows these devices to share space with WiFi equipment without requiring the device to log into the separate WiFi network. This allows data from/to the cellular device to utilize both the provider's carrier frequencies and the unlicensed 5 GHz spectrum.
As illustrated in FIG. 2, a Policy and Charging Control (PCC) interface 150 is used by LTE for monitoring and reporting licensed spectrum usage. The PCC includes a Policy and Charging Rules Function (PCRF) and a Policy and Charging Enforcement Function (PCEF). The PCRF generates rules enforced by the PCEF, which provides user traffic handling and Quality of Service (QoS) at the P-GW 32 over the user plane. The PCEF further provides service data flow detection and is able to differentiate between online and offline charging interactions.
The PCEF 160, part of the P-GW 32, communicates with the PCRF 140 over a Gx interface. The PCEF 160 also connects to both an online charging system (OCS) 154 and an offline charging system (OFCS) 156, via Gy and Gz interfaces, respectively. The PCRF 140 connects with an application function 130 over an Rx interface.
For unlicensed spectrum usage by the user equipment, the operators (e.g., AT&T or Verizon) may have different charging policies or rates. For example, data downloads may incur one charge while voice calls may incur a different charge, even though both operations are performed by the same user equipment. Currently, data usage is monitored and charged in the core network. This is because all the data go through the PCEF entity 160 in the P-GW 32.
However, with LTE-U enabled networks, where the unlicensed spectrum is utilized through carrier aggregation with the licensed spectrum, the PCEF 160 is unable to differentiate between data going through licensed and unlicensed spectrum. Only the eNB 40 is able to monitor such usage due to its direct involvement in scheduling resources over both the licensed and unlicensed spectrum at the air interface.
Currently, eNB does not have any role in user's data usage monitoring and charging aspects. As a result, with the currently standardized LTE systems, when unlicensed spectrum is leveraged through LTE-U technology, a mechanism to effectively monitor and report (and thus charge users) is beyond the current capabilities of the LTE network.
Thus, there is a desire for unlicensed spectrum monitoring and reporting that overcomes the shortcomings of the prior art